Black Spot on Cymbidiums: Fungus vs. Virus

Understanding Cymbidium Leaf Spotting

Your Cymbidium shows rapid black/brown spotting after rain exposure. This is common in modern miniature hybrids, which have sacrificed disease resistance for compact size.

Fungal Management (Primary Approach)

• Spray copper-based fungicide (e.g., Kocide by DuPont) weekly on new growth.
• Copper buildup on leaves extends protection.
• Keep leaves dry; increase air movement; avoid high humidity.
• Repot in fresh fir bark mix—old mix stays too wet.

Viral Possibility (If Fungicide Fails)

Cymbidium mosaic virus causes similar symptoms. No cure exists. Sterilize tools between plants; isolate infected plants to prevent spread via insects or sap contact.

Source for Resistant Plants

Buy from Santa Barbara Orchid Estate (find via "The Orchid Mall" under "S" suppliers). They offer superior, virus-tested Cymbidiums.